What is Alimony:
Payment that a family court may order one person in a couple to make to the other person when that couple separates or divorces. Alimony is an award for support and maintenance that one spouse may be compelled to pay to another after dissolution of the marriage,

In the common legal sense of the word, alimony is the allowance which by order of the court a husband pays to his wife for her maintenance while she is living separately from him, or the allowance or provision ordered by the court to be paid by her former husband to a divorced woman. There are two kinds of alimony, the one kind, alimony pendente lite, being an allowance to the wife pending a suit between herself and her husband, and the other the allowance or provision after suit, and which is known as permanent alimony. Source :>> http://www.newadvent.org/cathen/01313a.htm

American version of alimony with definition.:

For example, suppose two individuals who married in 1985 agree in 1995 to divorce. At the time of the divorce, the husband earns $63,000 a year, after seven years at a large company where the top pay for his specialty is $80,000. When the couple married, he was in graduate school and the wife was earning $22,000. The wife worked for three more years, supporting the husband while he completed his coursework and graduated.
When their first child was born, they agreed that the wife would care for the child at home. At the time of divorce, the wife had been working full-time for one year since the couple’s children, ages seven and six, had entered school. She was earning $23,000 a year and would have custody of the children.
A judge in this case would certainly award child support and would probably divide marital property equally between the couple. But it might not seem fair to the judge to allow the husband to leave the marriage with the sole possession of the couple’s most valuable asset—his earning potential—when the wife contributed to his education by supporting him.
Unlike the family’s home or station wagon, the husband’s earning power has not yet reached its full value, but it promises to grow. It seems especially unfair for the wife not to receive a share of it since after helping the husband attain his education she agreed to forfeit her earning power to invest time in the family. The several years she spent out of the workforce continue to handicap her earnings. Alimony is the only means available to the court to avoid a potentially unjust division of assets.

Source : http://legal-dictionary.thefreedictionary.com/alimony

Scenario 1: When I Found a job in a big metropolitan city, Im in search of accommodation; I asked my friends to look one for me. They found one lady ready to share her house, as she was staying alone. She told my friends that she will take huge amount of Advance or surety and Rent, but when I moved in she did not asked any nor after that. She was working in managerial capacity so she did not wanted any money as a rent, I was cooking myself, so she also joined me, as she liked my home food. She was out of house most of the house, and I was coming home early then I started to do house work cleaning also. She was paying all maintenance and bills of the house even every week she was ordering weekly ration / groceries. I hardly paid anything, as she knew I earn meager amount. As time passed by we drew closer and end up in BED together, we both enjoyed, I fulfilled all her fantasies and wild desires.

Later after few years I fell in love with other girl, and she found out.
  After this incident, she asked me to vacate her house.
  I went to Police and gave complaint that she is harassing me and asking to vacate her house.

BUT POLICE DID NOTHING AND THEY REFUSE TO TAKE MY COMPLAINT.

I went to court asking support as I was homeless, and with meager salary it is difficult maintain myself in big metropolitan city.

COURT ALSO DID NOT TAKE MY CASE.

SCENARIO 2: I was having good job and my own house and very good reputation in society. I found a girl where I was working and she moved in with me and we started to live together. She was receptionist and she was working in fix time, so she was coming home early. I was in management position, so my timing was differing everyday. As she was coming early she was cooking and cleaning, and we got physical too. Most of the time I was coming late, business meeting and out of town visits. once I went to other town and told her Ill be back after a week, but within 2 days I fell ill and I returned back to find this girl with her lover on my own bed.

I asked her leave my house immediately, but she went to police and reported, that Im harassing her and asking dowry.

Police registered complaint on her one word, without varifing any facts, Even there was no enquiry or investigation; and I was in jail for 15 days till I got bail. Not only me she charged my old parents who never visited us and they were in 1000Km far away native place. All are booked under Dowry and domestic violence Act.

When I came out of jail, she already got Court order to not to vacate her, and restrain me from my own house.

In America (USA) wife is entitled for alimony on this example can be justified.(Ref:to receive a share of it since after helping the husband attain his education she agreed to forfeit her earning power to invest time in the family. The several years she spent out of the workforce continue to handicap her earnings) 

BUT, THIS IS WHAT HAPPENS IN INDIA. (Two Scenarios)

When marry Indian women bring nothing, nor her parents give anything to Man / Husband
When man goes to police, complaining about his wife, Police never take any complaint, Even he produce proofs of threats and wound.
When husband caught wife with her extra marital Affairs she can file dowry case and domestic Violence case on husband, even his old parents ho never visited her.
Women can legally occupy husband house, even she never contribute anything to build the house.
Even Husband is forced to pay her Alimony, Even he caught her Red handed.

As Per Scenario #1
If man goes to police they will not take complaint.
Police will not arrest her
Even she work and earn huge amount man is not entitled for alimony.

Now the question is:
We all know Wife hardly bring anything WHEN SHE MARRY
She will not contribute ANYTHING to build house.
What she do as a housewife, cooking and cleaning, servants also can do for less.
In sex man is the not the only one WHO enjoy, she IS also enjoy.

So when she leaves for her own fault why Indian men forced to pay ALIMONY.
Why she get half of his Property, along with all gifts he gave.
WHY THIS PARTIALITY
WHY THIS STEP MOTHER POLICY.
WHY ALIMONY.